Yellowstone Lake is the site of actions to suppress invasive Lake Trout Salvelinus namaycush and restore native Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri and natural ecosystem function. Although gill netting is effective (Lake Trout λ ≤ 0.6 from 2012 through 2018), the effort costs more than US$2 million annually and only targets Lake Trout age 2 and older. To increase suppression efficiency, we developed an alternative method using organic (soy and wheat) pellets to increase mortality of Lake Trout embryos on spawning sites. Decomposition of pellets during two in situ experiments caused dissolved oxygen (DO) concentrations to temporarily decline to lethal levels (<3.4 mg/L) within days of application. Embryo mortalities during the first exposure period (days 1–6 following application) were high at all treatment levels (1.75–28.0 kg/m²) at the substrate surface and within interstices 20 cm below the surface, varying from 97 ± 1.8% (mean ± SE) to 100 ± 0.0%, but may have been enhanced by a handling effect (exposure to sunlight). Embryo mortalities during the second exposure period (days 11–22) were highest 20 cm below the surface, varying from 78 ± 9.7% to 100 ± 0.0%. Almost all (98 ± 3.1%) Lake Trout embryos died after exposure to DO < 3.4 mg/L for >200 h during the second period. Pellets caused lethal DO for several weeks below the substrate surface, despite largely dissolving and dissipating from the surface of treated areas by day 39. Broad‐scale application of pellets at 1.75 kg/m² following the spawning period in autumn may reduce Lake Trout recruitment and enhance population suppression because the area of 14 verified spawning sites is only 11.4 ha (0.03% of lake surface area). Pellet application may be useful in other similar systems as part of an integrated pest management approach targeting multiple life stages of invasive freshwater fish.

中文翻译：

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有机颗粒分解诱导黄石湖鳟鳟鱼胚胎的死亡率

黄石湖是镇压入侵鳟鱼Salvelinus namaycush并恢复本地黄石割喉鳟鱼Oncorhynchus clarkii bouvieri的行动地点和自然生态系统功能。尽管刺网是有效的（从2012年到2018年，鳟鱼湖λ≤0.6），但这项工作每年花费超过200万美元，并且仅针对2岁及以上的鳟鱼湖。为了提高抑制效率，我们开发了使用有机（大豆和小麦）颗粒的替代方法，以增加产卵点鳟鱼湖胚胎的死亡率。在两个原位实验中，颗粒的分解导致溶解氧（DO）浓度在施用后数天内暂时下降至致死水平（<3.4 mg / L）。在所有治疗水平下，第一次暴露期（施用后1-6天）的胚胎死亡率都很高（1.75-28.0 kg / m ^2））在基材表面以及低于表面20 cm的空隙内，从97±1.8％（平均±SE）到100±0.0％不等，但可能已因处理效果（暴露于阳光下）而增强。在第二个暴露期（第11至22天），胚胎死亡率最高是在表面以下20厘米处，范围从78±9.7％到100±0.0％。在第二阶段中，暴露于DO <3.4 mg / L> 200 h后，几乎所有（98±3.1％）Lake Trout胚胎均死亡。尽管在第39天时药丸已从治疗区域的表面大量溶解和消散，但药丸仍在基质表面以下几周造成了致命的溶解氧。大规模应用药丸的剂量为1.75 kg / m ²在秋季产卵期之后，可能减少鳟鱼湖的招募工作并增强种群抑制力，因为14个经过验证的产卵场面积仅为11.4公顷（占湖泊表面积的0.03％）。在针对侵入性淡水鱼多个生命阶段的有害生物综合治理方法的一部分中，颗粒施用可能在其他类似系统中很有用。